The present invention relates to machinery used to produce composite wood products, and in particular relates to disks used in rotating disk-type wood strand orienter machinery.
Composite wood products such as oriented strand board (xe2x80x9cOSBxe2x80x9d), particleboard and the like are produced from wood particles or strands. Such strands are generally elongated (longer than they are wide), and it is desirable to have these strands aligned longitudinally and lying flat on the mat when producing OSB. During the manufacturing process, strands of wood are typically formed into mats with the orientation of the wood strands controlled by strand-orienting machinery. Generally, the quality of a composite wood product depends in large part upon how well aligned the wood strands are in the wood strand mat produced by the orienter.
Commonly used strand orienters employ rotating disks. One type of orienter known in the art is the xe2x80x9cStokesxe2x80x9d type of orienter, which is described in detail in U.S. Pat. No. 3,115,431, which issued on Dec. 24, 1963 to Stokes et al. This orienter uses a plurality of intermeshed rotating disks mounted on a plurality of substantially parallel shafts oriented in a plane beneath a supply of wood strands. The wood strands are permitted to fall down upon the disks, which, while turning, tend to align the strands longitudinally. The aligned strands fall between the disks to form a mat of strands on a platform or conveyor beneath the disks. The mat is accordingly formed of particles aligned generally longitudinally, although the strands are not perfectly aligned.
Another type of orienter known in the art, which also employs orienting disks, is the type known as the xe2x80x9cBxc3xcrknerxe2x80x9d orienter. The Bxc3xcrkner orienter is disclosed in U.S. Pat. No. 4,380,285, which issued on 19 Apr., 1983. In the Bxc3xcrkner orienter, disks on adjacent shafts are arranged in pairs in side-by-side relationship, defining passages for allowing strands of wood to pass through to form a mat.
The disclosures of the aforementioned Stokes and Bxc3xcrkner patents are incorporated herein by reference.
Over many years, various types and shapes of orienting disks have been used in Stokes and Bxc3xcrkner orienters to orient wood strands. One type of disk commonly used today is shown in FIG. 1 (the xe2x80x9cprior art diskxe2x80x9d). This prior art disk has a generally circular shape, with protuberances formed along its periphery. Shallow notches are also cut into the periphery, the notches having a rear edge extending inwardly towards the center of the disk, and a forward edge extending upwardly and forwardly from the bottom of the rear edge, as described in greater detail below.
As discussed earlier, better quality wood composite products can be formed from wood strand mats having a high percentage of strands that are aligned longitudinally as well as lying flat on the mat, and the improved orienting disk of the present invention provides better strand alignment than the prior art disk.
The present invention provides an improved orienting disk for use in a wood strand orienter. In one embodiment of the invention the orienting disk comprises a plate having a generally circular shape and an outer periphery. An aperture is formed through the center of the plate for allowing the plate to be fitted onto a shaft in the wood strand orienter for rotation in a first direction about a rotation axis. A plurality of fin-shaped teeth extend outwardly from the periphery of the plate.
Each one of the teeth has a leading edge extending outwardly from the periphery of the plate to a tip of the tooth, the leading edge facing the first direction of rotation when the disk is fitted onto the shaft; and a trailing edge trailing rearwardly and downwardly from the tip of the tooth to the periphery of the plate.
In another embodiment of the invention, the fin-shaped teeth number between two and eight and are evenly spaced about the periphery of the plate. In yet another embodiment, there are six fin-shaped teeth, and each one of the teeth is separated from another by 60xc2x0 about the periphery of the plate.
The leading and trailing edges can be straight or curved, but in a preferred embodiment, the leading edge is straight, and the trailing edge is curved.
In another preferred embodiment, protuberances are formed about the periphery of the disk, between the fin-shaped teeth.